Get HTTP Request Method Overview

🛠️ Creating a FastAPI Application

In this course, we will use Visual Studio Code as our primary editor. You can also use any IDE you’re comfortable with, such as PyCharm.

In FastAPI, a GET request fetches data from the server. It does not modify any data — it simply retrieves information.

Step 1: Create a FastAPI Project (Quick Setup)

1. Create a new project folder FastAPI

Through the desktop →

Through the terminal (recommended) →

2. Open it in your editor (for this course, we’ll be using VS Code).

3. Create a virtual environment to isolate your project from other projects (recommended).

mac users →

// Create.
python3 -m venv fastapienv

// Activate.
source fastapienv/bin/activate

windows users →

// Create
python -m venv fastapienv

// Activate
fastapienv/scripts/activate.bat ---> command prompt
fastapienv/scripts/activate.ps1 ---> powershell

4. Install FastAPI and Uvicorn.

mac users →

pip3 install fastapi
pip3 install "uvicorn[standard]"

// pip3 ensures pip is using the same Python version as python3.

windows users →

pip install fastapi
pip install uvicorn[standard]

Step 2: Create the Application File

Create a file named books.py inside your project folder.

📂 Project Structure

FastAPI/
 └── books.py

Step 3: Write Your First FastAPI Code

🗂️ books.py

from fastapi import FastAPI
# Import the FastAPI class to create an API application.

app = FastAPI()
# Create an instance of the FastAPI app.

@app.get("/api-endpoint")
# Define a GET endpoint at "/api-endpoint."
async def first_api():
    return {"message": "Hello world"}
# Function that returns a JSON response.

🧠 Understanding Our Python Function

To make our Python function accessible from the web, we connect it to an HTTP GET request using a decorator (@).

@app.get("/api-endpoint")

Here, /api-endpoint is the URL path where this function will be available.

Let’s break down the function we created:

async def first_api():
    return {"message": "Hello world"}

🔹 The async keyword makes the function asynchronous, but it is optional.

FastAPI can handle async behavior automatically when needed.

🔹 Apart from that, this is just a normal Python function that returns data (a dictionary).

🚀 Starting the FastAPI Application

Run this command in the terminal:

uvicorn books:app --reload

🔧 What this command means:

• uvicorn → The server that runs FastAPI apps.

• books → Name of the Python file (books.py).

• app → The FastAPI instance inside that file.

• - - reload → Automatically restarts the server when you change code.

💻**terminal**

🌐 Accessing the Endpoint from the Browser

When you start the FastAPI app, a local server runs at:

🔗 127.0.0.1:8000

To call the function, open this URL in your browser:

🌍 127.0.0.1:8000/api-endpoint

You will see the response:

{"message":"Hello world"}

🌐**browser**

🔁 Returning a List of Books Instead of a Message

Now let’s return real data instead of a simple text response.

📚 Sample Book Data

🗂️ books.py

from fastapi import FastAPI

app = FastAPI()

BOOKS = [
    {"title": "Title One", "author": "Author One", "category": "science"},
    {"title": "Title Two", "author": "Author Two", "category": "science"},
    {"title": "Title Three", "author": "Author Three", "category": "history"},
    {"title": "Title Four", "author": "Author Four", "category": "math"},
    {"title": "Title Five", "author": "Author Five", "category": "math"}
] #sample book data.

@app.get("/api-endpoint") #we will update this soon.
async def first_api():
    return {"message": "Hello world"} #returns a message.

🔄 Update the Endpoint

❌ Old endpoint

@app.get("/api-endpoint") #old endpoint.
async def first_api():
    return {"message": "Hello world"}

✅ New endpoint

@app.get("/books") #updated endpoint.
async def read_all_books():
    return BOOKS #returns a list of books.

✅ Final Result

🗂️ books.py

from fastapi import FastAPI

app = FastAPI()

BOOKS = [
    {"title": "Title One", "author": "Author One", "category": "science"},
    {"title": "Title Two", "author": "Author Two", "category": "science"},
    {"title": "Title Three", "author": "Author Three", "category": "history"},
    {"title": "Title Four", "author": "Author Four", "category": "math"},
    {"title": "Title Five", "author": "Author Five", "category": "math"}
]

@app.get("/books")
async def read_all_books():
    return BOOKS

✅ View All Books

Restart the server and open:

🌍 127.0.0.1:8000/books

NOTE →

If you have an issue restarting the server, kill the terminal,

ctrl + C

then start the terminal again.

uvicorn books:app --reload

🌐**browser**

You will now see a JSON response containing all books.

📌 Summary

• GET requests are used to fetch data from the server.

• FastAPI connects URLs to Python functions using decorators → @

• Uvicorn runs the application locally.

• Endpoints can easily return different data (like a list of books).

This simple pattern is the foundation for building real-world FastAPI applications.